Neutronic design performance of 100 MWe MSR with thorium-enriched uranium and thorium-plutonium-minor actinide fuel

Molten Salt Reactors offer fuel flexibility, allowing the use of different starting fuels, including U-233, U-235, and Pu-239. U-233 is not a fissile nuclide that is commercially accessible. However, it can be produced through the utilization of the thorium cycle. In this paper, the neutronic performance of MSR with a power output of 100 MWe is analyzed for Th-U(enriched) and Th-Pu-MA as a starting fuel. The fuel composition is varied to show the neutronic parameter change and obtain the reactor criticality for five years of operation time. The calculation used SRAC Program and JENDL 4.0 as nuclear data libraries. It was found that the reactor with a Th-U fuel case can be operated in critical condition with a minimal fuel loading of UF4 of 7.30 mol%. Similarly, in the Th-Pu-MA fuel case, a minimal amount of PuF4 is at least 3.87 mol%. The Th-U fuel case exhibits a higher initial keff and reactivity swing compared to the Th-Pu-MA fuel case. At the end of the reactor cycle, the Th-U fuel produces several plutonium isotopes, such as Pu-238, Pu-239, Pu-240, Pu-241, and Pu-242. In contrast, the density of plutonium isotopes in the Th-Pu-MA fuel decreases during operation such as Pu-239 and Pu-241. Therefore, using Th-Pu-MA fuel is a viable approach to reducing spent nuclear fuel, as it reduces the number of plutonium isotopes.